Integumentary – The Skin

The Integumentary System comprises the cutaneous membranes (from superficial to deep: the epidermis, dermis, and subcutaneous hypodermis), as well as accessory structures.

The epidermis is further divided into five layers (superficial to deep) which are all mostly keratinized and dead: the stratum corneum, lucidum (thick skin only), granulosum, spinosum, and basale. In contrast, the dermis is divided into the vascularized papillary and reticular layers, and contains accessory structures such as the hair bulb, arrector pili muscle, dermal mechanoreceptors, various glands, etc. Lastly, the hypodermis consists primarily of adipose tissue, and covers the underlying muscle fascia.